1. Field of the Invention
This invention relates generally to lasers and more particularly to techniques for cooling and triggering of flash lamps used for optically pumped lasers. More specifically, the present invention relates to a cooling jacket apparatus having an integrally formed trigger wire assembly for parallel excitation of a flash lamp disposed within the jacket.
2. Description of the Prior Art
In the laser art, as progressively higher output powers are obtained, whether from pulsed or continuously running lasers, more and more stringent requirements are encountered for the thermal environment in which the laser device must operate. In its most basic form, control of the thermal environment of a laser device is exercised by cooling of the lasing medium by a flow of cooled gases or liquids over the materials per se, or over heat sinks which draw from the lasing materials. Recent advances in the field of solid state lasers using total internal reflection (TIR) within face pumped lasers (FPL) for development of the optical path for beam forming have added new dimensions to the thermal problems to be addressed. A part of the problem is due to the interaction of the cooling fluid with the total internal reflection within the laser material, alternately host material, resulting from the range of refractive indices of the fluid in which the laser is immersed. Another part of the problem is due to a reduction in laser output power because of thermally induced optical distortion in the laser materials. Clearly, the advance in performance of the newer laser devices will continue to depend on successfully resolving the thermal problems incurred.
A significant source of heat within the TIR-FPL, or in any optically pumped laser, is the flash lamps used for pumping of the host material. For an overview description of a TIR-FPL system, reference may be had to the publication "Total Internal Reflection Face Pumped Laser: Concept and Design Consideration" by G. J. Hulme and W. B. Jones, General Electric Company, Binghampton, N.Y., or to U.S. Pat. Nos. 3,679,999 of J. A. Chernoch; 3,581,229 of Martin; 3,500,231 of Tomiyasu and Almasi; 3,466,569 of Chernoch; and 3,423,693 of Chernoch and Koenig, all of which are assigned to the assignee of the present invention.
A representative prior art technique for cooling of laser devices and the flash lamps associated with them is provided in U.S. Pat. No. 3,679,999 to Chernoch, assigned to the assignee of the present invention. The Chernoch patent teaches the technique of removal of heat from solid state laser material via the combination of a gas layer in contact with a high thermal conductivity solid all of which is heat sinked by a cooling fluid.
Beyond the heat problems, operation of the flash lamps themselves has received attention due to their requirements for high voltages both to inititate and to maintain their light producing arc. Representative prior art teaching techinques for energizing these flash lamps--and especially the parallel triggered type--is provided in U.S. Pat. Nos. 4,010,397 to Hon and 4,047,064 to Cosco et al. Both patents address the problems associated with providing parallel triggering arrangements for flash lamps without reference to cooling considerations.
It is therefore a principal object of the present invention to overcome the disadvantages attendant in the prior art approaches, and to provide improved apparatus for cooling of optically pumped laser devises by exercising control over the thermal and optical environment of the flash lamp associated therein.
A further object of the present invention is to provide a cooling jacket of optical quality glass for surrounding a flash lamp such that coolant fluid may be flowed over the lamp to remove unwanted heat therefrom.
Another object of the present invention is to incorporate a trigger wire assembly within a cooling jacket such that the assembly becomes an integral part of the jacket and the combination may be used with a variety of flash lamp types and sizes.
Another object of the present invention is to provide a trigger wire electrode totally embedded in glass such that the trigger wire assembly positioned within the aforementioned cooling jacket is isolated from and thus precludes direct electrical contact of the trigger wire with the coolant medium. This arrangement increases the useful life of the components by eliminating harmful electrochemical processes otherwise resulting from electrical contact of the trigger element with the coolant.
Another object of the present invention is to decrease the size and weight of the power supplies required for parallel triggering of flash lamps by positioning of the trigger wire as close as feasible to its associated lamp, while retaining the thermal advantages resulting from immersing the flash lamp in coolant.